Multiple-ply web structures serve many purposes, such as for redeemable coupons with an upper layer peelable from a lower layer mounted directly on a product. Currently, the industry utilizes multiple webs introduced through a printing press having printing stations for each color on every ply of the finished multiple-ply label or coupon. The current process also requires the application of a glue which is applied in liquid form and then permitted to cure or dry. Once the glue has cured, the upper ply of the multiple-ply structure can be removed from the lower ply and the glue surface should be dry to the touch.
Typically, the multiple-ply process calls for printing of the upper ply separately from the lower ply and then subsequent steps of registering the upper ply with the lower ply and applying glue and varnish. Thus, for a structure having a five color upper ply with single color back printing, and a five color lower ply, and of the type where protective varnish was required, the conventional process would require a printing press with thirteen individual printing stations to produce the multiple-ply structure. In such a case, the sequence would be as follows: (1) print the five color bottom label (five stations), print the five color top label (five stations), (2) print the single color on the back of the top label, (3) apply glue between the two plies, and (4) apply varnish to the surface of the top label. Thus, this sequence requires thirteen individual printing stations.
There are several drawbacks to this conventionally-utilized sequence. First, the number of printing stations to produce the end product is excessive. When operating a machine of this size, it becomes extremely difficult to monitor all phases of the process due to the size and length of the equipment. Thus, it is necessary to utilize more than one machine operator, or to install electronic devices to ensure accurate tension, accurate print registration, accurate ply-to-ply registration, and accurate label printing to die-cutting registration, all being maintained within acceptable tolerances.
Further, since it is fairly common for the upper and lower plies of a multiple-ply structure to utilize very similar graphics and colors, undesirable results can be obtained utilizing two separate printing processes, due to variances in the color or quality of the printing.
It is therefore a general object of the present invention to provide an improved apparatus for producing a multiple-ply web.
Another object of the present invention is to provide an apparatus for producing a multiple-ply web which eliminates separate printing of similar upper and lower plies.
A further object of the present invention is to provide an apparatus for producing a multiple-ply web which is adjustable to various width webs, and various label dimensions.
These and other objects will be apparent to those skilled in the art.